Tow truck switching means



y 2, 1967 D. M. EDGAR ETAL 3,316,856

TOW TRUCK SWITCHING MEANS Filed June 16, 1964 s SheetS-Sheet 1 I/VVE/VTORS. DAV/0 141.5064? GRAHAM A. JOHNSON ATTORNEYS.

y 2, 5 D. M. EDGAR ETAL 3,316,856

TOW TRUCK SWITCHING MEANS Filed June 16, 1964 3 Sheets-Sheet 2 INVENTO/FS. DAV/0 M. EDGAR GRAHAM A. JOHNSON ATTORNEYS.

y 1967 D. M. EDGAR ETAL 3,316,856

TOW TRUCK SWITCHING MEANS 3 Sheets-Sheet 5 Filed June 16, 1964 INVENTO/PS. DAV/0 M. EDGAR GRAHAM Ir. JOHNSON 9W ATTORNEYS.

United States Patent 3,316,856 TOW TRUCK SWITCHING MEANS David M. Edgar and Graham K. Johnson, Easton, Pa., assignors to SI Handling Systems, Inc., Easton, Pa., a corporation of Pennsylvania Filed June 16, 1964, Ser. No. 375,458 9 Claims. (Cl. 104- 172) This invention relates to a tow truck switching means wherein a tow truck may be caused to be diverted from movement along a main slot to movement along a shunt slot.

Tow trucks of the type which are adapted to be used in conjunction with the present invention can assume a wide variety of sizes and shapes. Such tow trucks are well-known to those skilled in the art and have been widely adopted by industry. Thus, see for example, the tow trucks and systems in Patents 2,619,370, 3,103,183 and 3,103,895. The trucks is said patents are exemplary of those which may be utilized in conjunction with the switching means of the present invention.

The switching means of the present invention is associated with a reference surface such as the floor in a building. The reference surface has a main slot which is intersected at spaced points therealong by shunt slots. Adjacent the intersection of each shunt slot and the main slot, there is provided a switchplate member mounted for rotation about an axis which is generally perpendicular to the plane of the reference surface. The switchplate member has a contact surface such as a pocket and is biased to a position on one side of the main slot.

Selectively operable means, preferably responsive to actuation by a selector rod on a tow truck, are provided adjacent the switchplate member and structurally interrelated therewith. When actuated, the selectively operable means moves the switchplate member to a position wherein its pocket is disposed within the main slot. The tow pin of a truck engages the pocket in its last-mentioned disposition and causes the switchplate member to move. Such movement of the switchplate member by the tow pin causes the tow pin to move through a path whereby the tow pin is directed into the shunt slot. Thereafter, the switchplate member will return to its inoperative position.

It is an object of the present invention to provide a novel tow truck switching means.

It is another object of the present invention to provide a tow truck switching means which is caused to be moved from an operative to an inoperative position by means independent of the tow pin.

It is another object of the present invention to provide a switching means which is biased to an inoperative position and thereby is subjected to less wear.

It is another object of the present invention to provide a switchplate having a pocket for receiving and engaging a tow pin and guiding the same to the entrance of a shunt slot.

Other objects will appear hereinafter.

For the purpose of illustrating the invention, there are shown in the drawings forms which are presently preferred; it being understood, however, that this invention is not limited to the precise arrangements and instrumentalities shown.

FIGURE 1 is a partial top plan view of a switching means in accordance with one embodiment of the present invention.

FIGURE 2 is a view similar to FIGURE 1 but illustrating the components in an operative disposition.

FIGURE 3 is a sectional view taken along the line 3-3 in FIGURE 1.

FIGURE 4 is a sectional view taken along the line 4-4 in FIGURE 3.

FIGURE 5 is a partial plan view of a switching means in accordance with another embodiment of the present invention.

FIGURE 6 is a sectional view taken along the line 6--6 in FIGURE 5.

FIGURE 7 is a plan view of the main slot and a shunt slot in accordance with another embodiment of the illvention.

FIGURE 8 is a sectional view along line 88 in FIG- URE 7.

Referring to the drawing in detail, wherein like numerals indicate like elements, there is shown in FIGURES 1-4 a switching means designated generally as 10 for a tow truck system. The switching means 10 includes a reference surface 12, such as a floor or the like, having a main slot 14 therein. Below the main slot 14, there is generally provided a drag line or conveyor means 15, shown in phantom in FIGURE 5. The drag line 15 includes an upstanding driving dog 17, which is adapted to contact the tow pin of a tow truck and thereby propel the truck along the main slot 14. The tow truck is shown partially and in phantom in FIGURE 5, and is designated by the numeral 21.

The main slot 14 is intersected at spaced points therealong by a plurality of shunt slots which may extend to either side of the main slot. As illustrated in FIGURES 1 and 2, the main slot 14 is intersected by a shunt slot 16. The shunt slot 16 has an entrance portion 18. The angle between the entrance portion 18 and the main slot 14 is smaller than the angle between the shunt slot 16 and the main slot 14. The intersection 19 of main slot 14 and entrance portion 18 is reduced in thickness for a purpose to be described hereinafter.

On one side of the main slot 14, the reference surface 12 is provided with a large irregular shape cut-out portion 20.

On the opposite side of the main slot 14, the reference surface :12 is provided with a smaller and generally arcuate cut-out portion 22. The cut-out portions 20 and 22 facilitate rotation of a switchplate member 24.

switchplate member 24 is rotatably supported by an upright shaft 26. Shaft 26 is supported at its lower end by a subsurface 29 and supports the member 24 for rotation about an axis which is generally perpendicular to the reference surface 12. It will be noted that the shunt slot 16 and shaft 26 are on opposite sides of the main slot 14.

A torsion spring 28 is disposed around the shaft 26. One end of the spring 28 is secured to the sub-surface 29. The other end of the spring 28 is connected to the switchplate member 24. It will 'be noted that the switchplate member 24 lies generally in the plane of the reference surface 12. As shown more clearly in FIGURES 1 and 2, the switchplate member 24 is wedge-shaped. Between the intersection of the leading edge 32 and the arcuate periphery, plate member 24 is provided with a fingerlike projection 30 having an arcuate concave surface 34 defining a pocket. It will be noted that the spring 28 biases the switchplate member 24 to an inoperative posi tion wherein the pocket 34 is disposed to one side of the main slot '14.

As shown more clearly in FIGURE 3, the switchplate member 24 is provided with a depending abutment pin 36. A lever arm- 38 engages the periphery of the pin 36 and has a notch 39. The arm 38 is rotatably supported by pin 40 for rotation about its longitudinal axis which is generally perpendicular to the reference surface 12. Lever arm 38 is integral with arm 42. which extends downwardly from the reference surface 12 and terminates in a generally horizontal portion 44.

Lever arm 38 is adapted to berotated about the pin 40 'by means of a bell crank having arms 46 and 48.

. respect to the dragline or conveyor means.

Arms '46 and 48 are integral and mounted for rotation about the longitudinal axis of pin 50. Pin 50 is supported by the reference surface 12 by a pair of lugs. Arm 46 has its lower end extending through a hole in the portion 44. The reference surface 12 is provided with a hole 52 through which extends an abutment 54. Abrutment 54 is secured to the arm 48 and is provided with a cam surface 56.

The tow truck adapted to be utilized with the switching means of the present invention will have one or more selector rods 58 supported thereon and a tow pin 60 which enters the main slot 14. If the selector rod and tow pin are in line with one another, the abutment 54 will be disposed so as to be contacted by the selector rod before the tow pin reaches a position wherein it could contact the switchplate member 24. As illustrated in FIGURES 1 and 2, the selector rod 58 is positioned so that it is supported by the truck forwardly of the tow pin 60.

The operation of the embodiment illustrated in FIG- URES 1-4 is as follows:

It will be assumed that the elements are in the position illustrated in FIGURE 1. Further, it will be assumed that a tow truck is being propelled along the main slot 14 by contact between the tow pin 60 and a dragline or conveyor means (not shown). Further, it will be assumed that the selector rod 58 has been positioned on the tow truck so as to cause the tow truck to be switched into shunt slot 16.

As the tow truck moves along the main slot 14, the selector rod 58 will engage the cam surface 56 and cause the arms 46 and 48 to rotate in a clockwise direction in FIGURE 4. Such rotation of arm 46 causes arm 38 to rotate from the position in FIGURE 1 to the position in FIGURE 2. Since the pin 40 is substantially closer to projection 44 than to pin 36, only a short are of rotation is required by the projection 44 to obtain a sufficiently large arc of rotation by the tip or free end of arm 38. Such rotation of arm 38, due to its engagement with the abutment pin 36, rotates the switchplate member 24 from the position in FIGURE 1 to the position in FIGURE 2 against the bias of spring 28.

The required amount of rotation for the switchplate member 24 is that amount of rotation necessary to move the pocket 34 from its inoperative position in FIGURE 1 to its operative position in FIGURE 2. As soon as the pocket 34 is in the position in FIGURE 2, pin 36 is received in notch 39 to hold pocket 34 in a position wherein the tow pin 60 will engage the pocket 34 and cause the switchplate member 24 to continue to rotate in the direction of arrow 62. By providing notch 39 on arm 38, the invention does not require precise timing of the member 24 with respect to tow pin 60.

Such further movement of the switchplate member 24 from the position in FIGURE 2 in the direction of arrow 62 is effected by the tow pin 60, and during such movement the tow pin 60 is moved laterally by the switch plate member 24 and thereby becomes disengaged with When the switchplate member 24 has rotated to a position wherein the finger projection 30 is disposed over the left hand end of intersection 19, the pocket 34 is disposed so as to enable the tow pin 60 to move into the portion 18 and continue into the shunt slot 16 under its own momentum. It is to be understood that the portion of intersection 19 having reduced fitness permits passage of the finger projection 30 thereover. The tow pin 60 will leave contact with the pocket 34 shortly after entering the portion 18. Thereafter, the spring 28 will return the switchplate member 24 to the position illustrated in FIGURE 1. Arm 38, the bell crank, and abutment 54 will have moved to the position illustrated in FIGURES 1 and 4 due to counter weight balancing of the bell crank.

In the above-mentioned Patent 3,103,183, the switch plate member is biased to a position wherein a tow pin is caused to enter the shunt slot. In the switching means of the present invention, the switchplate member is biased to an inoperative position wherein no switching will occur. In accordance with the present invention, the switch plate member is mounted for movement with the tow pin to guide the tow pin into a shunt slot. In Patent 3,103,- 183, the switchplate member is stationary during switching. As opposed to the switching means in Patent 3,103,- 183, the switchplate members 24 or 24' are moved to an inoperative position independently of the tow pin. That is, in the present invention, the tow pin does not cam the switchplate member to its inoperative position. In the switching means of the present invention, the tow pin and switchplate member are moving together at the same rate of speed. Hence, there is little or no wear on the switchplate member.

In FIGURES 5 and 6, there is illustrated another embodiment of the present invention designated generally as 10'. The switching means 10 is identical with the switching means 10 except as will be described hereinafter. Accordingly, corresponding elements are provided with corresponding primed numerals.

In switching means 10', the selectively operable means for rotating the switchplate member 24' to a position wherein the pocket 34' may engage the tow pin 60 includes a cable 66. One end of cable 66 is adjustably coupled to the lowermost end of arm 46. From arm 46, the cable 66 extends around pulleys 68 and 70 supported by the surface 29'. From pulley 70, the cable 66 extends upwardly through a guide 72 and has its other end connected to an arm 74. Arm 74 is fixedly secured to and depends from the switchplate member 24'. It will be noted that arm 74 is positioned adjacent the trailing edge 64 on the switchplate member 24.

Due to the position of the arm 74, it may travel in substantially a straight path during that portion of the rotary movement of the switchplate member 24' necessary to place the pocket 34' in the required position for engagement with the tow pin 60. In order to prevent the cable 66 from becoming tangled due to slack, it is provided with a limit stop 76 adapted to engage the guide 72. The limit stop 76 is preferably spaced from the guide 72 by a distance corresponding to the distance that the lowermost end of the arm 46 will travel. Hence, the cable 66 will not become dislodged with respect to the pulleys 68 and 70.

Switching means 10' may have an overload protection device designed generally as 100. Device 100, as illustrated includes an actuator 102 movably supported in shunt slot 16 for engagement with tow pin 60. Actuator 102 is biased to the position shown and is coupled to member 24' by way of a flexible member such as cable 104 which in turn engages pulleys 106 and 108. One end of cable 104 is connected to arm 110. Arm 110 is fixedly coupled to a free end of a portion of cable 66. The other end of said portion of cable 66 is connected to arm 74.

A spring 112 interconnects arm 110 and an end of another portion of cable 66 adjacent limit stop 76. Spring 112 is stronger than spring 28. When actuator 102 is in the position shown, there is sufficient slack in 104 so that the member 24 may be activated to switch tow pin 60' into shunt slot 16 as described above. When .a predetermined number of trucks have been switched into shunt slot 16, corresponding to the capacity of slot 16, the next truck on the towline while pushing the switched trucks will force the tow pin of the first truck into contact with actuator 102 and pivot the same about pins 115 and 117, thereby tensioning cable 104. Thereafter, movement of abutment 54' will merely result in spring 112 being stretched rather than causing movement of switch member 24' to a position wherein tow pin 60' can contact pocket 34'. When actuator 102 is permitted to return to the position illustrated, additional trucks may be switched to shunt slot 16'.

In FIGURES 7 and 8, there is illustrated another tow cable truck system of the present invention designated generally as 170. In tow truck system 170, the switching of a truck (not shown) is accomplished at the intersection of the main slot 174 and shunt slot 176 in the surface 172. Such switching may be accomplished without moving the tow pin 198 on the truck. Thus, the tow pin 198 is merely moved aside, without appreciable vertical movement. The truck supporting the tow pin 198 may be completely conventional and therefore it was not deemed necessary to illustrate the same.

An abutment 178 is supported by the surface 172. Abutment 178 is movably supported for rotation about a horizontal axis. One end of the abutment 178 projects upwardly above the surface 172 while the lower end of abutment 178 projects downwardly into a space below the surface 172. The lower end of the abutment 178 is coupled to one end of a flexible member 180 which may be a wire, cable, rope, or the like. Flexible member 180 extends around pulleys 184 and 185. The other end of flexible member 180 is coupled to one end of a flexible support 186 having a latch 182 thereon. Support 186 may be a leaf spring or the like.

An arm or switch member 188 terminating in a hook portion or pocket 190 is rotatably supported by a shaft 192 with a loose fit. A torsion spring 196 extending between the shaft 192 and arm 188 biases the arm 188 to the solid line disposition illustrated in FIGURE 8.

In the region of the intersection of the main slot 174 and the shunt slot 176, there is provided a curved cam surface 194 which guides the arm 188 through an arcuate path as it rotates about the shaft 192. System 170 may be provided with an overload protection device 102' which performs the same function as device 100. One end of cable 104' is connected to actuator 102' and the other end of cable 104 is connected to arm 188 as illustrated. Actuator 102' is biased to the position shown.

The operation of the system 170 is as follows:

It will be assumed that the arm 188 and hook portion 190 are in the phantom position illustrated in FIGURE 8. The latch 182 maintains the arm 188 in this phantom disposition. It will be assumed that a truck supporting tow pin 190 is guided for movement along the main slot 174 and has a trip rod supported by a selector rack. As soon as the trip rod contacts the abutment 178, the abutment 178 is rotated in a counterclockwise direction in FIGURE 8.

Such rotation of the abutment 178, through the medium of the flexible member 180, rotates the latch 182 in a clockwise direction as illustrated by the arrow in FIG- URE 8 with the support 186 flexing during such movement. As soon as the latch 182 has moved out of a blocking disposition, the spring 196 rotates the arm 188 to the solid line position illustrated in FIGURES 7 and 8. Shortly after the arm 188 has rotated to the solid line disposition in FIGURES 7 and 8, the tow pin 198 will have moved to the disposition illustrated in FIG- URE 7 and will be trapped within the hook portion 190. Thereafter, continued movement of the truck under inertia and the conventional conveyor dog will cause the arm 198 to be rotated about the axis of shaft 192 and the truck to be transferred from movement along the main slot 174 to movement along the shunt slot 176.

As the thusly switched truck is moving, it pushes the arm 188 thereby causing the :arm 188 to rotate about the shaft 192 and against the bias of spring 196. Since the arm 188 is also guided by the cam surface 194, it gradually descends along the lower portion of the tow pin 198 until it is clear of the same and is trapped behind the latch 182.

Thereafter, the above sequence of operations may be repeated :for lefthand or righthand switching as desired. It will be obvious to those skilled in the art that the loose fit between the arm 188 and the shaft 192 will enable the arm 188 to move through the arcuate path defined by the cam surface 194. To more easily facilitate the arcuate movement of the arm 188, the upright shaft 192 is preferably provided with a longitudinal axis perpendicular to the line 199 and generally perpendicular to surface 172. In view of the above description of device 100, it is not deemed necessary to describe device 102' in detail. When shunt slot 176 has reached its capacity, the actuator 102 is moved to a position wherein cable 104 prevents arm 188 from rotating.

In each embodiment, the switch member is moved to an operative position for contact with the tow pin and then moves with the tow pin until the tow pin enters the shunt slot. It is within the scope of the invention to utilize a reciprocable switch plate member.

The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof and, accordingly, reference should be made to the appended claims, rather than to the foregoing specification as indicating the scope of the invention.

It is claimed:

1. Tow truck switching means for switching a tow truck having a depending tow pin for engagement with a slot comprising a reference surface having a main slot intersected by at least one shunt slot, a switch member movably supported adjacent said intersection, means mounting said member for movement from an inoperative position to an operative position, said member in its operative position presenting an abutment surface in the main slot for contact with a tow pin, said member being mouned for movement from said operative position with the tow pin to guide the tow pin into the shunt slot, means for causing said member to remain in its inoperative position, and means supported by said reference surface and actuable by a portion of a truck for moving said member from its inoperative position to its operative position, said last-mentioned means including an abutment which when actuated causes said member to move to its operative position.

2. Switching means in accordance with claim 1 includ ing an overload protection device coupled to said switch member to render the same incapable of movement to said operative position after the shunt slot is loaded to a predetermined number of trucks.

3. Switching means in accordance with claim 2 wherein said device includes a flexible member a portion of which is generally parallel to said shunt slot.

4. Switching means in accordance with claim 1 wherein said switch member is mounted for rotation about an axis generally perpendicular to said reference surface.

5. Tow truck switching means in accordance with claim 1 wherein said shunt slot and switch plate member are on opposite sides of the main slot, a portion of the shunt slot adjacent said intersection with the main slot being curved with the axis of curvature thereof corresponding to said upright axis.

6. Tow truck switching means in accordance with claim 1 wherein said reference surface is provided with a cutout portion of larger peripheral area than said switch plate, said switch plate being received within said cut-out portion.

7. Truck switching means in accordance with claim 1 wherein said shunt slot has an entrance portion, the included angle between said entrance portion and said main slot being less than the included angle between said main slot and the remainder of said shunt slot.

8. Tow truck switching means in accordance with claim 7 wherein said portion is of reduced thickness so that a portion of the switch plate may overlie the same during switching of a tow pin from movement along the main slot to movement along the shunt slot.

9. Tow truck switching means for switching a tow truck having a depending tow pin for engagement with a slot comprising a reference surface having a main slot intersected by at least one shunt slot, a switch member movably supported adjacent said intersection, means mounting said member for movement from an inoperative position to an operative position, said member in its operative position presenting an abutment surface for contact with a tow pin of a truck to be switched into the shunt slot adjacent said member, an abutment supported by said reference surface for generally downward movement with respect to said surface, means structurally interrelating said abutment and member so that the member moves to its operative position in response to downward movement of the abutment, and control means disposed along the shunt slot for mechanically rendering the movement of the abutment ineffective insofar as operation of the switch member is concerned when a predetermined number of trucks accumulate along the shunt slot, said control means including a contact member movably supported along a shunt slot for contact with a tow pin disposed in the shunt slot, and said contact member being coupled to said switch member to cause the latter to remain in its inoperative position when the predetermined number of trucks corresponding to the capacity of the shunt slot have accumulated along the shunt slot. 7

References Cited by the Examiner UNITED STATES PATENTS 1,124,268 1/1915 Bernhcim 104--170 2,619,370 11/1952 Leger 104-172 X 2,660,127 11/1953 Boyko et al 104 -172 2,782,727 2/1957 King 104172 2,982,228 5/1961 Bishop et al. 104172 3,076,419 1/1963 Dehne 104172 3,103,183 9/1963 Bradt et al. 104-172 3,103,895 9/1963 Bradt et al 104-88 ARTHUR L. LA POINT, Primary Examiner.

F. W. MONAGHAN, D. E. HOFFMAN,

Assistant Examiners. 

1. TOW TRUCK SWITCHING MEANS FOR SWITCHING A TOW TRUCK HAVING A DEPENDING TOW PIN FOR ENGAGEMENT WITH A SLOT COMPRISING A REFERENCE SURFACE HAVING A MAIN SLOT INTERSECTED BY AT LEAST ONE SHUNT SLOT, A SWITCH MEMBER MOVABLY SUPPORTED ADJACENT SAID INTERSECTION, MEANS MOUNTING SAID MEMBER FOR MOVEMENT FROM AN INOPERATIVE POSITION TO AN OPERATIVE POSITION, SAID MEMBER IN ITS OPERATIVE POSITION PRESENTING AN ABUTMENT SURFACE IN THE MAIN SLOT FOR CONTACT WITH A TOW PIN, SAID MEMBER BEING MOUNED FOR MOVEMENT FROM SAID OPERATIVE POSITION WITH THE TOW PIN TO GUIDE THE TOW PIN INTO THE SHUNT SLOT, MEANS 